This invention relates to hydrophobic pigment dispersants, to compositions containing them, and to compounds for defoaming them.
Pigment dispersants, especially hydrophobic pigment dispersants, are known to both generate and stabilize large quantities of foam when added to aqueous compositions containing pigments.
This foaming propensity is highly disadvantageous, and is particularly troublesome when the dispersants are used to disperse pigments present in water-based paints.
This invention relates to aqueous-based compositions containing pigments and pigment dispersants, and more particularly to compositions containing pigment dispersants, especially hydrophobic pigment dispersants, and a branched polymer as a defoaming agent.
The branched polymers used in the above compositions are the reaction products of a linking agent defined by formula (I):
R(Y)3xe2x80x83xe2x80x83(I)
wherein each Y group is a halogen atom or one Y group is a halogen atom and two Y groups together represent an epoxy oxygen atom, which is attached to two adjacent carbon atoms in the R group to form an epoxy group, and R is an alkanetriyl group containing from 3 to 10 carbon atoms, the preferred linking agent being epichlorohydrin; and at least one compound having the formula (II)
R1X(EO)n(PO)m(BO)pZxe2x80x83xe2x80x83(II)
wherein R1 is a substituted or unsubstituted, saturated or unsaturated, organic group having from 4 to 36 carbon atoms; x is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, or xe2x80x94NR2xe2x80x94where R2 is hydrogen or a C1-C4 alkyl group; Z is hydrogen, xe2x80x94NHR2 in place of a terminal xe2x80x94Oxe2x80x94 group wherein R2 has the meaning given above, or xe2x80x94SH, in which the xe2x80x94SH group is present in place of a terminal xe2x80x94Oxe2x80x94 group; n is a number of from 0 to 100, e.g., from 1 to 100; m is a number of from 0 to 50 e.g., from 1 to 50; and p is a number of from 0 to 50 e.g., from 1 to 50; provided that the sum of n, m, and p is at least 1;
wherein EO represents the residue of ethylene oxide, PO represents the residue of propylene oxide, and BO represents the residue of butylene oxide; and wherein the EO, PO and BO groups when present can be in random and/or block distribution and can be in any order with respect to the X group. When the term xe2x80x9cbranched polymerxe2x80x9d is used herein it is to be understood to refer to one or more of the above reaction products.
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term xe2x80x9caboutxe2x80x9d. Also, throughout this description, unless expressly stated to the contrary; percent, xe2x80x9cpartsxe2x80x9d of, and ratio values are by weight; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description or of generation in situ by chemical reactions specified in the description, and does not necessarily preclude other chemical interactions among the constituents of a mixture once mixed.
In the branched polymers used in the practice of the invention, in the formula II reactant, formula II compounds wherein the sum of n, m, and p is at least 2, especially at least 3, are preferred. Examples of R1 groups include substituted or unsubstituted alkyl groups having from 4 to 36 carbon atoms, preferably from 4 to 22 carbon atoms, alkenyl and alkynyl groups having from 4 to 36 carbon atoms, preferably from 4 to 22 carbon atoms, aryl groups having from 6 to 26 carbon atoms, and arenyl groups having from 7 to 36 carbon atoms. When the above groups are substituted groups, the groups can contain single or multiple substitutions such as a halogen substitution, for example CI, FI, I and Br. a sulfur functionality such as a mercaptan or thio group; a nitrogen functionality such as an amine or amide functionality; a silicon functionality; or any combination thereof.
The R1 group can be any substituted or unsubstituted, saturated or unsaturated organic moiety having from 4 to 36 carbon atoms. Thus, the R1 groups can be linear or branched alkyl groups, linear or branched alkenyl or alkynyl groups, saturated carbocyclic moieties having one or more multiple bonds, saturated heterocyclic moieties, unsaturated heterocyclic moieties having one or more multiple bonds, substituted linear or branched alkyl groups, substituted linear or branched alkenyl or alkynyl groups, substituted saturated carbocyclic moieties, substituted unsaturated carbocyclic moieties having one or more multiple bonds, substituted saturated heterocyclic moieties, and substituted unsaturated heterocyclic moieties having one or more multiple bonds. Examples of the above include but are not limited to an alkyl group having form 4 to 22 carbon atoms, an alkenyl group having from 4 to 22 carbon atoms, and an alkynyl group having from 4 to 22 carbon atoms. R1 can also be an arenyl group. Arenyl groups are alkyl-substituted aromatic radicals having a free valence at an alkyl carbon atom such as a benzylic group. Alkyl groups having from 4 to 12 carbon atoms are preferred, and alkyl groups having from 8 to 10 carbon atoms are most preferred. The degree of ethoxylation is preferably from 2 to about 50, more preferably from 3 to about 50, with the most preferred being from 4 to 50, while the degree of propoxylation and butoxylation can vary from 0 to about 50, e.g. from 0 to about 10. The degree of propoxylation and/or butoxylation will be determined by the desired degree of water solubility or miscibility. The water solubility or miscibility will ultimately be determined by such factors as the number of carbon atoms in R1 , the relative amounts EO, PO and BO, and the effect of PO and BO on the biodegradability of the branched polymer. The water solubility or miscibility of a branched polymer according to the invention and the interrelationships between the number of carbon atoms in R1, the relative amounts of EO, PO and BO and the biodegradability of the final product will be readily determinable by one of ordinary skill in the art.
When the Z group of formula (II) is a mercapto group, examples of such compounds include but are not limited to, alkoxylated dodecyl mercaptan and alkoxylated 1-hexadecanethiol.
When the X group is xe2x80x94NR2xe2x80x94, the compounds of formula (II) are alkoxylated amines. When the compounds of formula II are alkoxylated amines, n is a number from 0 to 50, preferably from 1 to 50, m is a number from 0 to 50 and p is a number from 0 to 50, preferably from 1 to 50, provided that the sum of n, m, and p is at least 1. Examples of the alkoxylated amines useful for the purposes of the invention include but are not limited to, alkoxylated dibutyl amine, alkoxylated dicyclohexyl amine, alkoxylated diethylethanolamine, and alkoxylated dioctylamine.
The mole ratio of the linking compound (I) to (II) is from about 0.4/1 to about 5/1, preferably from about 0.4/1 to about 2/1 and more preferably from about 0.6/1 to about 1.6/1.
Optionally an additional component can be reacted with the linking agent of formula (I) and the compound of formula (II). A glycidyl ether or amine can be added to the reaction of formula (I) and formula (II). The amount of the glycidyl ether or glycidyl amine is from about 1 to about 20 mole percent based on the moles of the compounds of formula (II) used in the reaction. When the glycidyl ether or glycidyl amine is added to the monofunctional starting material of formula (II), the ratio of formula (I) to formula (II) plus the glycidyl ether or glycidyl amine is preferably from about 0.8 to about 1.4. Examples of the glycidyl ethers include but are not limited to, PEG 600 Diglycidyl ether, TETRONIC(trademark) 701 Tetraglycidyl ether, Triglycidyl DI or Triethanolamine, Polyoxyethylene (POE) 200 Tallow amine diglycidyl ether, Propoxylated (POP10) Trimethylol propane triglycidyl ether, Propoxylated (POP7) Pentaerythritol tetraglycidyl ether. Examples of Glycidyl amines include but are not limited to, Tetraglycidyl-1,6-Hexane diamine, Tetraglycidyl JEFFAMINE(trademark) EDR-148, and Tetraglycidyl Isophorone diamine.
In the reaction products used in the invention, the linking agent of formula (I) is preferably epichlorohydrin although other epihalohydrins can be used. Also, trihaloalkanes can be used, such as 1,2,3-trichloropropane, 1,2,4-trichlorobutane, 1,3,6-trichlorohexane and the like. Instead of chlorine in the epihalohydrins and the trihaloalkanes, the corresponding bromine and iodine compounds can also be used, including compounds containing two or even three of the above halogens.
In the compounds of formula II where Z is xe2x80x94NHR2, the corresponding compound of formula II wherein Z is xe2x80x94OH can be converted to xe2x80x94CI or xe2x80x94Br and then reacted with ammonia or a C1xe2x80x94C4 primary amine. Where Z is xe2x80x94SH, the corresponding compound in which Z is xe2x80x94OH can be converted to the mercaptan by methods well known to the art, e.g. by the reaction of the corresponding xe2x80x94CI or xe2x80x94Br compound with sodium hydrosulfide.
Preferred compounds of formula II have the following formula III:
R1O(EO)n(PO)m(BO)pHxe2x80x83xe2x80x83(III)
in which R1 , n, m, and p have the meanings given above.
In the compounds of formula II and III, it is understood that EO stands for the residue of ethylene oxide, PO stands for the residue of propylene oxide and BO stands for the residue of butylene oxide. Also, in the compounds of formula II and III, the EO, PO, and BO groups, when present, can be in any order with respect to the R1 X or R1 O group, and can be in blocks and/or in random distribution, although the alkoxide groups present are preferably present in the order shown in formulae II and III.
The reaction between reactants A) and B) can be carried out by reacting the components at a temperature in the range of from 90 to 150xc2x0 C., preferably from 100 to 110xc2x0 C., in the presence of a basic catalyst, such as a concentrated aqueous alkali or alkaline earth metal hydroxide. Sodium hydroxide and potassium hydroxide are preferred. The reaction is preferably carried out in the presence of an inert organic solvent that azeotropes water, i.e. toluene, and at a temperature that drives off the azeotrope.
The pigment dispersants are anionic polymeric pigment dispersants, and are usually copolymers or terpolymers of maleic anhydride or maleic acid, e.g. diisobutylene/maleic anhydride copolymer and a terpolymer of maleic anhydridelmethacrylic acid/styrene.
Compositions containing a pigment dispersant and a branched polymer can be used as an additive to disperse pigments in aqueous-based products. These compositions can be anhydrous or can be diluted with water if desired. The branched polymer is present in the compositions in a quantity of from 0.05% to 20%, preferably from 0.05 to 5% and more preferably from 0.1 to 2.5%, based on the weight of pigment dispersant. Such relatively small quantities of branched polymer results in virtually no stable foam when the composition is added to pigment-containing aqueous based products, such as latex paints and the like. In addition, the branched polymer is miscible in the pigment dispersant, resulting in a clear, homogeneous product.
When the compositions containing the pigment dispersant and the branched polymer are used to disperse pigments in aqueous-based paint compositions, substrates coated with the resulting paint exhibit a coating that is even, bubble-free, and has exceptionally high gloss combined with very high water resistance.
While the branched polymers are preferably combined with pigment dispersants to be used as additives to pigmentxe2x80x94containing aqueous-based products, the pigment dispersants and the branched polymers can of course be added separately. The same relative quantity of branched polymer, based on the quantity of pigment dispersant, is added to the pigmentxe2x80x94containing aqueous based product.
In general, the pigment dispersant, whether combined with the branched polymer as an additive, or added separately, is generally added in a quantity of from 0.05 to 2.0% dispersant solids, based on the weight of the pigment in the product.
The pigmentxe2x80x94containing aqueous based products can be paints or other pigmentxe2x80x94containing products such as filled adhesives, rubber/polymeric materials (e.g. carpet backing), stucco, grouts, textured coatings, cements, concrete, pigment dispersion concentrates, caulks, sealants, paper coatings, and highly filled thermosetting polymer systems.
Latex paint compositions can contain, in addition to pigments, latex polymer particles, thickeners, protective colloids, flow agents, surfactants, catalysts, wetting agents, other defoamers, and plasticizers. Pigments that can be used in latex paints include, but are not limited to, titanium dioxide (rutile), mica, calcium carbonate, clay, talc, silica and wollastonite. Some of the above pigments are sometimes referred to as extended pigments.
The invention will be illustrated but not limited by the following examples.